Piezoelectric coaxial cable having a helical inner conductor

Abstract

A piezoelectric coaxial cable comprising a metallic helically wound inner conductor, the volume within the helix being filled with a solid material; a continuous piezoelectric polymer layer circumferentially surrounding the inner conductor; and an outer conductor in contact with the piezoelectric polymer layer but separated from the inner conductor.

We claim: 
     
       1. A piezoelectric coaxial cable comprising (a) a metallic helically wound inner conductor, the volume within the helix being filled with a solid material;   (b) a continuous piezoelectric polymer layer circumferentially surrounding the inner conductor; and   (c) an outer conductor in contact with the piezoelectric polymer layer but separated from the inner conductor.   
     
     
       2. A piezoelectric coaxial cable according to claim 1 further comprising a continuous circumferential conductive polymer layer in contact with the inner conductor and the piezoelectric polymer layer but separated from the outer conductor. 
     
     
       3. A piezoelectric coaxial cable according to claim 1 or claim 2 wherein the piezoelectric polymer layer comprises a vinylidene fluoride polymer. 
     
     
       4. A piezoelectric coaxial cable according to claim 1 or claim 2 wherein the piezoelectric polymer layer comprises vinylidene fluoride homopolymer. 
     
     
       5. A piezoelectric coaxial cable according to claim 1 or claim 2 wherein the volume within the helix is filled with a conductive polymer. 
     
     
       6. A piezoelectric coaxial cable according to claim 1 or claim 2 further comprising an electrically insulating jacket over the outer conductor.